A conventional rotary charging plug structure of a charger, such as that disclosed in ROC (Taiwan) Patent Application No. 82201253 entitled "Improved Rotary Charging Plug Structure of a Charger" (as shown in FIGS. 1 and 2), mainly comprises a housing 100 having walls, and a plug structure 200. The housing 100 includes a substantially L-shaped notch 110 that is formed with openings 120. The two openings 120 are formed therebetween with a receiving slot 130 for receiving an urging element 140. The receiving slot 130 is formed at a bottom thereof with a blind hole 150 at a location corresponding to where the urging element 140 is provided. The blind hole 150 may be provided with a spring 160 therein. The urging element 140 is further formed at an outer end thereof with a semi-circular protrusion 141. The plug structure 200 includes a horizontal shaft 210, two coupling plates 220, and blades 230. The coupling plates 220 and the shaft 210 are integrally joined to one another by riveting so as to allow free rotation with respect to one another. The coupling plates 220 are inserted and retained within the notch 110 of the housing 100. The horizontal shaft 210 is inserted between the two coupling plates 220 and blades 230. The horizontal shaft 210 is formed with keyways 210 at each of opposing ends thereof for engaging with another ends of the blades 230 and rotating along with the blades 230. The horizontal shaft 210 is formed with a semi-circular groove 211 at a location corresponding to the semi-circular protrusion 141 of the urging element 140 so as to prevent the semi-circular groove 211 and the semi-circular protrusion 211 from disengagement when the horizontal shaft 210 rotates along with the blades 230 about a tip of the semi-circular protrusion 141.
The above structure, however, consists of the following disadvantages:
1. Because the horizontal shaft is inserted after the coupling plates are integrally joined to the blades by riveting, a frontal or a lateral impact applied to the blades may cause disengagement of the semi-circular protrusion 141, the spring 160, or the keyways 212 thereby causing inconvenience in use.
2. Such a structure consists a great number of components, which increases manufacturing cost arisen from production, component management, and assembly.
3. In use, the blades must be directly inserted into the slots of a receptacle; any slight deviation in orientation may cause the blades to flip upwards to their storage positions thereby causing much incontinence.
4. Due to prolonged use, the indoor or outdoor humidity may result in elastic deformation or rust of the spring thereby causing failure of its original function.
In view of the above disadvantages, multiple trails and experiments are performed to obtain the rotary charging plug structure of a charger of this invention.